via Wikipedia: Self-balancing two-wheeled board
A self-balancing two-wheeled board, or self-balancing electric scooter, also commonly referred to as a “ overboard”, is a type of portable, rechargeable battery-powered scooter. They typically consist of two wheels arranged side-by-side, with two small platforms between the wheels, on which the rider stands. The device is controlled by the rider’s feet, standing on the built-in gyroscopic, sensored pads.
In 2014, several such devices appeared in China, and by 2015, they became widely popular in the United States, following numerous celebrity appearances with the device.There is no universally accepted name for the device, as its various product names are attributable to the companies which distribute it and not its manufacturers.
via Wikipedia: Hoverboard
For the type of scooter sometimes known by this name, see Self-balancing two-wheeled board.
Thank you Wikipedia editors. You’re my only hope for sanity.